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1

I'm not sure if this is what you are looking for, but here goes: For example, Benshuai Lyu & Ann P. Dowling have studied the effects of lobed nozzles on installed jet noise. The article displays graphs plotting frequency vs. decibel of variable arrangements of jet nozzles. The graphs go up to 20kHz, which would be the upper limit of audible spectrum (*. ...

5

No that has no benefits for aviation at all, except for the marketing department. A large amount of losses funnelling the airflow from motor to a small strip, from which it is propelled at high velocity. As stated in many places on this site, thrust T = $\dot m \cdot \Delta V$, while the energy expelled E$_{kin}$ = $½ \cdot \dot m \Delta V^2$. So thrust ...

2

It has roughly 50% lower energy density than jet fuel, so obviously worse, but still much better than any rechargeable batteries. If we could use it directly in fuel cells, which generally have efficiencies approaching 60%, which is twice as good as piston and turbine engines, then we could actually get a system performance similar to that of jet fuel. A big ...

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